Process for preparation of arylterpenoid insect maturation inhibitors

Abstract

There is provided an improved process for producing biologically active arylterpenoid compounds useful to inhibit eclosion of pupae, e.g., fly pupae or mosquito pupae. The process is characterized by reacting a terpenoid material having a terminal unsaturated linkage, e.g., dihydromyrcene (3,7-dimethylocta-1,6-diene) with a lower alkyl Grignard reagent, e.g., n-propyl magnesium chloride to form a Grignard exchange product. The exchange product is then benzylated. Either a benzyl halide, e.g., p-isopropylbenzyl chloride, or a benzaldehyde, e.g., p-isopropylbenzaldehyde may be used. These compounds are specifically described in U.S. Pat. No. 4,002,769. They contain also a lower alkoxy group, e.g., methoxy. This can be introduced prior to the formation of the Grignard exchange product or at a later stage in the operation. Use of the exchange-type Grignard reaction enables elimination of several steps when producing the arylterpenoids from pinene as the terpene source, and consequent costs.